Torque monitoring system and method of a hybrid electric vehicle

Abstract

A torque monitoring system and method of a hybrid electric vehicle is provided that accurately monitors and diagnoses a compensation torque, such as an intervention torque generated from the vehicle's perspective and an engine friction torque, in addition to a driver's request torque. The torque monitoring system includes a control unit configured to: determine final command torques for respective power sources; determine a requested torque for monitoring based on vehicle driving information; determine compensation torques for the respective power sources depending on whether an engine clutch is engaged based on intervention torques for the respective power sources and additional torques for the respective power sources; determine a command torque limit value; and determine whether there is an abnormality in each torque determination process based on the determined command torque limit value and a sum of the determined final command torques for the respective power sources.

What is claimed is: 
     
         1 . A torque monitoring method of a hybrid electric vehicle, comprising:
 determining, by a control unit, final command torques for respective power sources by adding intervention torques for the respective power sources and additional torques for the respective power sources for torque compensation to command torques for the respective power sources distributed from a driver's requested torque;   determining, by the control unit, a requested torque for monitoring based on vehicle driving information;   determining, by the control unit, compensation torques for the respective power sources depending on whether an engine clutch is engaged based on the intervention torques and the additional torques;   determining, by the control unit, a command torque limit value that is a sum of the determined requested torque and the determined compensation torques; and   determining, by the control unit, whether there is an abnormality in a torque determination process at each operation based on the determined command torque limit value and a sum of the determined final command torques for the respective power sources.   
     
     
         2 . The torque monitoring method of  claim 1 , wherein each of the intervention torques for the respective power sources comprises:
 an internal intervention torque determined internally by the control unit to control vehicle motion; and   an external intervention torque received from outside.   
     
     
         3 . The torque monitoring method of  claim 2 , wherein the intervention torques for the respective power sources comprise an engine intervention torque and a motor intervention torque. 
     
     
         4 . The torque monitoring method of  claim 3 , wherein:
 the compensation torques for the respective power sources comprise an engine compensation torque and a motor compensation torque;   the additional torques for the respective power sources comprise an additional engine torque and an additional motor torque; and   in a disengaged state of the engine clutch, the motor compensation torque is determined as a sum of the motor intervention torque and the additional motor torque, and the engine compensation torque is determined as zero.   
     
     
         5 . The torque monitoring method of  claim 3 , wherein:
 the compensation torques for the respective power sources comprise an engine compensation torque and a motor compensation torque;   the additional torques for the respective power sources comprise an additional engine torque and an additional motor torque; and   in an engaged state of the engine clutch, the motor compensation torque is determined as a sum of the motor intervention torque and the additional motor torque, and the engine compensation torque is determined as a sum of the engine intervention torque and the additional engine torque.   
     
     
         6 . The torque monitoring method of  claim 1 , wherein:
 the additional torques for the respective power sources comprise an additional engine torque and an additional motor torque;   the additional engine torque is determined as an engine friction torque; and   the additional motor torque is determined as a motor torque to compensate for a decrease or increase in engine output.   
     
     
         7 . The torque monitoring method of  claim 1 , wherein:
 the compensation torques for the respective power sources comprise an engine compensation torque and a motor compensation torque; and   the command torque limit value is determined as a sum of the requested torque for monitoring, the engine compensation torque, and the motor compensation torque.   
     
     
         8 . The torque monitoring method of  claim 1 , wherein, in determining whether there is the abnormality in the torque determination process at each operation, the control unit is configured to:
 diagnose that there is the abnormality in the torque determination process at each operation, when an absolute value of a difference between the command torque limit value and the sum of the determined final command torques is greater than or equal to a predetermined set value; and   diagnose that the torque determination process at each operation is normal, when the absolute value of the difference between the command torque limit value and the sum of the determined final command torques is less than the predetermined set value.   
     
     
         9 . A torque monitoring system of a hybrid electric vehicle, comprising a control unit,
 wherein when a driver's requested torque is determined and a drive mode of the hybrid electric vehicle is determined, the control unit is configured to:   determine command torques for respective power sources based on the driver's requested torque by distributing the driver's requested torque based on the drive mode;   determine final command torques for the respective power sources by adding intervention torques for the respective power sources and additional torques for the respective power sources for torque compensation to the determined command torques for the respective power sources,   determine a requested torque for monitoring based on vehicle driving information;   determine compensation torques for the respective power sources depending on whether an engine clutch is engaged based on the intervention torques for the respective power sources and the additional torques for the respective power sources;   determine a command torque limit value that is a sum of the determined requested torque and the determined compensation torques; and   determine whether there is an abnormality in each torque determination process based on the determined command torque limit value and a sum of the determined final command torques for the respective power sources.   
     
     
         10 . The torque monitoring system of  claim 9 , wherein each of the intervention torques for the respective power sources comprises:
 an internal intervention torque determined internally by the control unit to control vehicle motion; and   an external intervention torque received from outside.   
     
     
         11 . The torque monitoring system of  claim 10 , wherein the intervention torques for the respective power sources comprise an engine intervention torque and a motor intervention torque. 
     
     
         12 . The torque monitoring system of  claim 11 , wherein:
 the compensation torques for the respective power sources comprise an engine compensation torque and a motor compensation torque;   the additional torques for the respective power sources comprise an additional engine torque and an additional motor torque; and   in a disengaged state of the engine clutch, the motor compensation torque is determined as a sum of the motor intervention torque and the additional motor torque, and the engine compensation torque is determined as zero.   
     
     
         13 . The torque monitoring system of  claim 11 , wherein:
 the compensation torques for the respective power sources comprise an engine compensation torque and a motor compensation torque;   the additional torques for the respective power sources comprise an additional engine torque and an additional motor torque; and   in an engaged state of the engine clutch, the motor compensation torque is determined as a sum of the motor intervention torque and the additional motor torque, and the engine compensation torque is determined as a sum of the engine intervention torque and the additional engine torque.   
     
     
         14 . The torque monitoring system of  claim 9 , wherein the control unit comprises:
 a basic control logic unit configured to:
 determine the driver's requested torque, 
 determine the drive mode of the hybrid electric vehicle, 
 determine the command torques for the respective power sources based on the driver's requested torque, and 
 determine the final command torques for the respective power sources; and 
   a torque monitoring logic unit configured to:
 determine the requested torque for monitoring, 
 determine the compensation torques for the respective power sources depending on whether the engine clutch is engaged, 
 determine the command torque limit value, and 
 determine whether there is the abnormality in each torque determination process. 
   
     
     
         15 . The torque monitoring system of  claim 14 , wherein the torque monitoring logic unit is configured to:
 receive information comprising the command torques for the respective power sources based on the driver's requested torque, command torques for the respective power sources after reflecting the intervention torques for the respective power sources that are obtained by adding the intervention torques for the respective power sources to the command torques for the respective power sources based on the driver's requested torque, the additional torques for the respective power sources for torque compensation, the final torque commands for the respective power sources, and the drive mode of the hybrid electric vehicle, from the basic control logic unit; and   use the received information to determine the compensation torques for the respective power sources and the command torque limit value.   
     
     
         16 . The torque monitoring system of  claim 15 , wherein:
 the intervention torques for the respective power sources comprise an engine intervention torque and a motor intervention torque; and   the torque monitoring logic unit is configured to:
 determine the engine intervention torque as a value obtained by subtracting an engine command torque based on the driver's requested torque from an engine command torque after reflecting the intervention torques received from the basic control logic unit; and 
 determine the motor intervention torque as a value obtained by subtracting a motor command torque based on the driver's requested torque from a motor command torque after reflecting the intervention torques received from the basic control logic unit. 
   
     
     
         17 . The torque monitoring system of  claim 9 , wherein the additional torques for the respective power sources comprise an additional engine torque and an additional motor torque. 
     
     
         18 . The torque monitoring system of  claim 17 , wherein:
 the additional engine torque is determined as an engine friction torque; and   the additional motor torque is determined as a motor torque to compensate for a decrease or increase in engine output.   
     
     
         19 . The torque monitoring system of  claim 9 , wherein:
 the compensation torques for the respective power sources comprise an engine compensation torque and a motor compensation torque; and   the command torque limit value is determined as a sum of the requested torque for monitoring, the engine compensation torque, and the motor compensation torque.   
     
     
         20 . The torque monitoring system of  claim 9 , wherein the control unit is configured to:
 diagnose that there is the abnormality in each torque determination process, when an absolute value of a difference between the command torque limit value and the sum of the determined final command torques for the respective power sources is greater than or equal to a predetermined set value; and   diagnose that each torque determination process is normal, when the absolute value of the difference between the command torque limit value and the sum of the determined final command torques for the respective power sources is less than the predetermined set value.